Hardly any U.S. towns collect more precipitation than Oso: 72 inches a year
Nights in January average 33°. Expect the heaviest rain or snow in November and the lightest in July. In July, afternoons here are cooler than in 98% of U.S. towns. Homes need heating from October to April, the months averaging under 50°.
A year in Oso at a glance
Each month’s typical high and low, and what it brings.
What stands out about Oso’s climate
Compared with towns across the U.S., with Oso’s place in Washington beside it.
What a year in Oso feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 229 frost-free days a year
In half of years the last 32° night comes by March 28 and the first by November 14. Day counts come from NOAA’s station at Arlington, WA, 11 miles from the town’s center, 190 ft lower; frost dates and degree days from Concrete Ppl Fish Stn, WA, 19 miles away.
The 2023 USDA map puts Oso’s center in zone 8a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 15°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 16 inches of snow a winter
Snow, measured at Concrete Ppl Fish Stn, WA, falls mostly in December. Precipitation (rain plus melted snow) adds up to 72 inches a year; November is the wettest month and July the driest. Rain or snow falls on about 185 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Oso
97% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Concrete Ppl Fish Stn, WA.
Living with Oso’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
229 frost-free days in zone 8a. The last frost comes by Mar 28 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 14.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 1.9 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Oso from natural hazards, river flooding is the largest share (44%); heat waves, cold waves, winter storms and ice storms together are 3%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Oso and similar climates
TownRatings has no climate map of the towns around Oso yet.
Climates most like Oso’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Oso, WA | 33° | 75° | 72" | 16" |
| Boone, NC | 24° | 79° | 58" | 26" |
| Sandy, OR | 35° | 80° | 57" | 2.2" |
| Crossville, TN | 27° | 84° | 59" | 14" |
| Fortuna, CA | 42° | 70° | 55" | 0.7" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Oso averaged 0.9° warmer than the 1900s. The biggest change is in January (+2.7°).
A smaller shift than in 86% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Oso compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Oso’s place among Washington’s.
Oso weather by month
Highs, lows and precipitation from NOAA’s grid at Oso’s center; snow, wet days and snow on the ground from Concrete Ppl Fish Stn, WA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 43° | 33° | 10.2" | 5.0" | 21 | 7 | 32° – 43° |
| February | 46° | 33° | 6.6" | 1.5" | 18 | 2 | 31° – 45° |
| March | 51° | 35° | 7.9" | 1.3" | 20 | 1 | 38° – 50° |
| April | 57° | 38° | 5.3" | 0.0" | 18 | 0 | 43° – 53° |
| May | 64° | 44° | 3.8" | 0.0" | 14 | 0 | 49° – 59° |
| June | 68° | 48° | 2.9" | 0.0" | 13 | 0 | 54° – 63° |
| July | 75° | 52° | 1.3" | 0.0" | 7 | 0 | 59° – 67° |
| August | 75° | 52° | 1.6" | 0.0" | 6 | 0 | 59° – 66° |
| September | 70° | 48° | 3.4" | 0.0" | 10 | 0 | 56° – 62° |
| October | 58° | 42° | 7.6" | 0.0" | 17 | 0 | 46° – 55° |
| November | 48° | 36° | 11.5" | 0.9" | 21 | 1 | 38° – 46° |
| December | 42° | 33° | 9.7" | 7.6" | 21 | 3 | 33° – 41° |
| Year | 58° | 41° | 71.8" | 16.3" | 185 | 15 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 31° to 45°. September is the most reliable, staying within 6°.
Where Oso’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Oso’s center.
- Snow: Concrete Ppl Fish Stn, WA.
- Frost dates, heating and cooling: Concrete Ppl Fish Stn, WA, 19 miles away.
- Freezing nights, 90° and 100° days: Arlington, WA, 11 miles from the town’s center, 190 ft lower; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Oso’s climate
What is the weather like in Oso?
A typical July afternoon reaches 75°, a January night drops to 33°, and about 16 inches of snow falls in a normal winter. Milder January nights than 77% of U.S. towns; cooler July afternoons than 98% of U.S. towns.
How cold does it get in Oso in winter?
December nights average 33°. About 94 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 33°.
How much snow does Oso get?
About 16 inches in a normal winter at Concrete Ppl Fish Stn, WA, most of it in December, with snow on the ground about 15 days a year.
How hot does it get in Oso?
July, with a typical high of 75° and a low of 52°. About 5 days a year reach 90° (Concrete Ppl Fish Stn, WA).
When is the first and last frost in Oso?
In half of years the last spring frost (32°) comes by March 28 and the first fall frost by November 14, about 229 frost-free days, at Concrete Ppl Fish Stn, WA.
What growing zone is Oso in?
Zone 8a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 15°.
What is the best time of year to visit Oso?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Oso getting warmer?
Yes: 1991–2020 averaged 0.9° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 86% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Oso.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.